Abstract 6305: Downregulation of glutamine transporter stably and significantly attenuates weight loss by a cachexia-inducing pancreatic cancer xenograft
Authors: Balaji Krishnamachary, Ishwarya Sivakumar, Yelena Mironchik, Raj Kumar Sharma, Santosh Kumar Bharti, Marie-France Penet, Paul Winnard, Eibhlin Goggins, Jiefu Jin, Anirban Maitra, Michael G. Goggins, Zaver M. Bhujwalla
Journal: Cancer Research (2022)

Abstract Cancer-induced cachexia is commonly observed in pancreatic cancer. The syndrome induces significant weight loss and leads to morbidity, intolerance to chemotherapy, and mortality. While performing metabolic characterization of the brain and plasma of mice with a cachexia-inducing human pancreatic cancer xenograft we identified significant changes in glutamine metabolism [1] that led us to investigate the effects of altering tumor glutamine metabolism on weight loss. We genetically engineered cachexia inducing Pa04C cells to express shRNA downregulating the glutamine transporter SLC1A5. Tumors derived from Pa04C cells with downregulated SLC1A5 (CSh cells and tumors) exhibited significantly delayed tumor growth compared to empty vector (EV) or wild type (WT) tumors, but escaped growth delay approximately 60 days after inoculation, although SLC1A5 mRNA and protein remained significantly downregulated. Despite tumor growth, mouse weight reduction was significantly attenuated at matched EV and CSh tumor volumes. We next sought to investigate if tumors derived from cells isolated from escaped CSh tumor (TSh cells and tumors) continued to exhibit growth delay and attenuated weight loss when re-inoculated in mice. Quantitative transcriptome profiling by RNA-seq was performed to determine differentially expressed genes in CSh and TSh cells compared to EV cells. Method: EV, CSh or TSh cells were inoculated subcutaneously in male mice. Tumor volumes and weights of tumor bearing mice were recorded until tumors were harvested at ~ 500 mm3 for molecular characterization. RNA was isolated in triplicate from EV, CSh and TSh cells. Transcriptomic analysis was performed by RNA sequencing on a NovaSeq 6000 PE150 platform. All bioinformatics analysis was performed with assistance from the NOVOGENE informatics group. Results: Tumors derived from TSh cells did not exhibit any growth delay unlike tumors derived from CSh cells. SLC1A5 expression remained downregulated in TSh cells and tumors. Despite the loss of growth delay, mice with TSh tumors continued to exhibit attenuated weight loss identifying, suggesting the glutamine transporter as a potential treatment strategy to reduce cachexia. Transcriptomic analysis allowed us to identify the adaptive changes that occurred in CSh tumors that allowed these tumors to escape growth delay despite SLC1A5 downregulation. Transcriptomic differences between TSh and CSh cells were primarily in pathways related to amino acid metabolism, inflammation and the extracellular matrix. These transcriptomic differences allow the identification of novel targets that can be used in combination with glutamine transporter downregulation to arrest the growth of pancreatic cancer cells in vivo. Supported by NIH R35 CA209960 and R01 CA193365. 1) J Cachexia Sarcopenia Muscle. 2020 Dec; 11(6): 1487-1500. Citation Format: Balaji Krishnamachary, Ishwarya Sivakumar, Yelena Mironchik, Raj Kumar Sharma, Santosh Kumar Bharti, Marie-France Penet, Paul Winnard, Eibhlin Goggins, Jiefu Jin, Anirban Maitra, Michael G. Goggins, Zaver M. Bhujwalla. Downregulation of glutamine transporter stably and significantly attenuates weight loss by a cachexia-inducing pancreatic cancer xenograft [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6305.